As would be well known to one of skill in the art, the toe angle of a vehicle wheel is typically set during the vehicle manufacturing process. The toe angle is typically set by adjusting a tie-rod assembly associated with the wheel of interest. A tie-rod assembly commonly extends between the vehicle's steering assembly and a steering arm or similar component associated with each front wheel of the vehicle, such that rotation of the vehicle's steering wheel is translated into a turning of the vehicle's front wheels.
A tie-rod assembly typically includes an inner tie-rod and an outer tie-rod. The inner tie-rod normally threads into a like-threaded portion of the outer tie-rod. Frequently, at least a portion of the inner tie-rod may be of hexagonal or similar cross-section to facilitate rotation during threading of the inner tie-rod into the outer tie-rod. The tie-rod assembly may also include a lock nut that is installed over the threaded portion of the inner tie-rod and may be tightened against the outer tie-rod to secure the position of the tie-rod assembly.
As is common knowledge to one of skill in the art, the toe angle of a vehicle wheel is commonly set by adjusting the overall length of the tie-rod assembly. This is normally accomplished by adjusting the depth to which the inner tie-rod is inserted into the outer tie-rod. Once the proper tie-rod assembly length is achieved, the position of the tie-rods is secured via the lock nut or whatever other locking mechanism is associated with the particular tie-rod assembly of interest.
In order to most efficiently set toe angle during a vehicle manufacturing operation, the tie-rod assembly adjustment process has been automated. For example, it is known in the art to equip a robot with a powered tie-rod adjustment apparatus for this purpose. One such tie-rod adjustment apparatus is described and shown in U.S. Pat. No. 6,308,593 to Shibayama et al. Such a tie-rod adjustment apparatus commonly includes an open-end wrench portion with a driven rotating socket for selectively rotating a hex-shaped portion of an inner tie-rod and a lock nut used to secure the position of the inner tie-rod with respect to the outer tie-rod. A guide fork or similar element may also be provided to engage the outer tie-rod during a toe angle setting process. In operation, the robot appropriately locates the tie-rod adjustment apparatus to the tie-rod assembly and the tie-rod adjustment apparatus is operated to adjust the length of the tie-rod assembly—thereby setting the toe angle of the associated vehicle wheel.
Such tie-rod adjustment apparatus and their methods of use have proven effective in automatic toe angle setting operations. These known devices are not, however, without drawbacks. One particular drawback is associated with the manufacturing of more than one vehicle type on a given assembly line. More particularly, the drawback is associated with the fact that these various vehicle types also frequently employ tie-rod assemblies having dissimilar lock nut and/or inner tie-rod hex sizes. As such, a single tie-rod adjustment apparatus of the typical variety is unable to adjust the tie-rod assemblies of these different vehicles.
One solution to this problem has been to provide a dedicated tie-rod adjustment apparatus for each vehicle type for which a toe angle setting operation will be performed. At the time of vehicle changeover, the robot then performs a tool change, whereby the existing tie-rod adjustment apparatus is disengaged from the robot and the tie-rod adjustment apparatus designed for use with the new vehicle type is engaged.
The undesirable nature of this solution is readily apparent. First, such a solution requires the construction and storage of a number of different tie-rod adjustment apparatus. Further, such apparatus are often quite large and complex, and the need to perform a tool change in between vehicle types may require a temporary slow down or pause of the vehicle assembly line.
Recently, new tie-rod adjustment apparatus designs have been proposed to overcome the aforementioned tool change requirement. These apparatus are allegedly capable of operating on tie-rod assemblies having dissimilar sized components by employing an adjustable tie-rod engaging portion. However, these proposed designs employ highly complex assemblies of moving parts, clamping mechanisms, etc., that invite failure, increase maintenance, and drive up manufacturing costs.
It can be understood from the foregoing discussion that a better solution to operating on tie-rod assemblies having dissimilar sized components is desirable. Apparatus of the present invention provide such a solution.